1) Amoghapasha Mantra: Whoever sees, hears, remembers, or touches this mantra will be purified of all negativity and gain freedom from birth in the lower realms:
Om padmo ushnisha vimale hum phat
2) Vajrapani Mantra: clearing away obstacles and negativity:
Hung vajra phat
3) Manjushri Mantra: Speech of Manjushri
Om wagi shori mum
4) Opening the mandala:
Om Hum Tra Hrih Ah – Om Ah Hum Phat
5) Opening the chakras:
Om Ah Chakra Hum
6) Transforming inner fear: each of the syllables protects one of the five chakras
Om Ah Hum Swaha
7) Padmasambhava is alive:
Om Ah Hum Vajra Guru Padma Siddhi Hum (x108)
There are many ways of trying to explain the power of mantra. Maybe it is not worth thinking about. Even the Buddha said that the question “why are mantras effective?” can never be answered. Mantras are the continuing manifestations of the Sambhogakaya body of the Buddha. These syllables are the continuous vibrations of the sound of the Buddha. The pronunciation is not as important as intend, concentration, and practice. There is no wrong way to chant a mantra for it has purity by its very being.
There are many approaches to using the power of mantra. When you begin, just listen to the sound.
Then put the mind into the mantra. One’s being becomes the vibrations that are the mantra. Living the sound, it is possible to develop meditating mind, free from thoughts.
In another approach, one focuses attention on the mantra alone. This is a form of freedom from thoughts by exclusion. Of course, mantra can also be used devotionally or evocatively, or as a means of protection. Develop your own means of using the mantra. According to your needs, your abilities, and understanding. When in public, the mantra will still be effective if chanted silently to oneself. It will not be as effective but will still help.
Remember that these mantras are an important part of the tradition and not something to be treated lightly. Like seeds, they may not look like much but when used properly one will understand their potency and potentiality. It is one of the Wish Fulfilling Gems.
From TNMC Annals Tarthang Tulku Rinpoche